trawl2m 94jan 11jan94-06feb94 Macrozooplankton community abundance and composition from a 2m trawl. 2m metro trawl (1000 um mesh) towed in the upper 120 m to collect zooplankton and micronekton; the catch is used for: A. random samples (1) community composition and distribution (2) alternate scatterer abundances for analysis of acoustics biomass data taken at 120 kHz, i.e. scatterers other than antarctic krill (3) random sample of antarctic krill for length frequency and females with red thelycums (MF) which is subsequently preserved, and B. selected specimens (4) the source of antarctic krill for PHYCONA (physiological condition of adults) over the entire spatial scale of the cruise, which includes instanteous growth rate (krillGrowth) experiments on board spawning frequency (krillSpawn) experiments on board there are multiple files/directories generated from the analysis of the 2m trawl collections (1) file: trawl.list is a record of the trawl information for all trawls, including the 2-M trawl, and the catch disposition event #, trawl #, date, time begin (GMT), day/night, tow duration (min), LTER grid location, begin latitude decimal degrees and minutes, begin longitude decimal degrees and minutes, tow direction (heading), ship speed (kts), water depth (m), cloud cover (%), wind speed (kts), wind direction, gear (1m or 2m or midwater or IKMT trawls), tow type (oblique to standard depth, targetted tow or oblique to shallower depth because the bottom depth is shallow), target depth, volume filtered (m^3), time-depth-recorder (TDR) depth indication, TDR tow duration, catch split (yes or no), fish removed (y or n), other organisms removed (yes or no), preserved sample (yes or no; yes for the IKMT means specific items not a random sample). ¥ Organisms removed means different things depending whether or not there was a split of the catch. If there was no split, organisms may have been removed for other purposes (experiments or chemistry for example) so the preserved sample is not a totally random sample and therefore can only represent the community composition if the organisms removed are added back into the sample analysis. OR all rare organisms were removed before the split and preservation, for example, all silverfish larvae. OR salps were counted, a volume taken, representative individuals preserved, and the remainder thrown away. (2) file: trawl.catch is a record of the trawl catch composition with information of varying quality depending on the type of trawl and taxonomic group Event number, trawl number, transect, station, volume filtered (m^3), net size, tow type, tow depth (m from TDR), total volume of catch (ml), number and volume of E. superba, Thysanoessa sp., salps; number of E. crystallorophias, E. triacantha, Limacina sp., other pteropods, Themisto gaudichaudii, other amphipods; presence or absence of chaetognaths; number of antarctic silverfish larvae (Pleuragramma antarcticum), other fish larvae, and siphonophores. Method identification: 1=quantitative count on board of macrozooplankton; 2=quantitative for krill only; 3=qualitative. 0=absent; -5=present; -10=many. Comments include adult fish, tomopterid worms, whether salp numbers and volumes are also quantitative if qa/qc=2. (3) file: altscatter.dat is a record of the numbers and volumes of the presumed alternate scatterers from the 2m trawl catch record event number, trawl number, transect, station, volume filtered (m^3), tow type, tow depth, total volume of catch (ml), number and volume of E. superba, Thysanoessa sp., salps; number of E. crystallorophias, E. triacantha, Limacina sp., other pteropods, Themisto gaudichaudii, other amphipods, siphonophores. (4) directory: krill.raw Raw data on individual krill is recorded in files named for the event and tow number when there are > 10 E. superba in a catch. Data from the random sample of 100 krill measured and inspected for red thelycums on board is in EV**T**.raw. Variables are source of individual (fresh, preserved sample, growth experiment), total length (mm) and MF (mature female with red thelycum). (1) file: trawl.list volume filtered (meters cubed) = Net area * ((flow meter final reading - flow meter initial reading) * (26873/999999)) The last digit of the 7 digit flowmeter reading is 0.1 revolution and is simply dropped from the reading, so only 6 digits are recorded. When the meter "turns over", i.e., goes past 999999 back through zero a 1 should be added in front on the meter reading. For example, if FM initial = 878361, and FM final = 052787, it actually should be 1052787. (2) directory: krill.lfhist When the length data is from a random sample, it can be used to generate length frequency histograms. The raw data for lengths is binned by 0.5 mm length increments, from 9.5 to 58.5 mm, and saved as evt#.lfhist. The number of individuals in each length bin is the number with total lengths in the range of the bin id plus .49 mm, i.e., individuals measuring from 32.50 to 32.99 mm are in bin 32.50. Two-meter trawls were conducted at cardinal stations on 4 cardinal lines (600.*, 500.*, 400.* and 300.*) plus at selected stations during phase II within the 50 km radius of the Adelie penguin rookeries near Palmer to verify targets and at selected stations 'inside north' (LeMaire and Grandidier) and 'inside south' (Crystal Sound) as ice permitted. ***.raw and ***.lfhist files are available from selected 1m tows where there were not enough krill from the 2m catch, but krill were definitely found at the station. (1) trawl specifications: ¥ the 2m trawl is a Metro net, with a fixed frame 2-m on a side, and the bridle attachments in the middle of the side pieces of the frame; the mesh size for the net is 1000 µm and the codend is 500 µm; (2) protocol for deployment: ¥ a TDR is attached to the top of the frame, and a flow meter (General Oceanics) is attached to side of the frame so it hangs in the middle of the net opening; snap clips are used for easy removal ¥ the tow is an oblique tow to a standard depth of 120 m and back, water depth permitting. Wire out (m) and wire angle, measured from the stern, plus a wire angle chart is used to target the fishing depth of the net. This depth is verified by the TDR and the relationship between targetted depth and actual depth has been used to develop an empirical wire angle chart for this particular net/ship combination. The TDR depth is verified periodically by attaching it to the Bio-Optical Profiling System and comparing the BOPS depth and the TDR depth. ¥ all information for the trawl.list is recorded on a TRAWL RECORD sheet for each tow ; the TDR paper is taped to that sheet and the time and depth of the tow as measured by the TDR is recorded. (3) treatment of catch: The goal is (a) to characterize the total catch, i.e., numbers and volumes of each type of organism, and (b) to preserve, freeze, or use subsamples of our targetted species for several purposes. ¥ when the net comes on board the cod end is set gently into a large white tub (50 liters) filled one-third to one-half with cold seawater, then unclipped; if there are no krill the net is rinsed down with a hose, directly into the halibut tub; if there are krill, the air bubbles could affect their physiological condition so the cod end contents are poured gently into the tub, then the net is rinsed into the cod end and the contents poured into the tub ¥ the contents of the tub are sorted on board for macrozooplankton and micronekton, and samples measured, preserved and frozen as detailed in the following sections. TRAWL CATCH LOG contains the details of the catch processing and disposition of the catch (# and size of preserved jars and preservative (formalin or ethanol), # frozen and size of vial, # into IGR etc). (a) KRILL All krill are removed to a separate bucket/tub, either with a coarse mesh scoop or tweezers depending whether or not a growth experiment will be started. From the total catch of krill, the following samples are taken and data recorded: - krill tl/mf, with volume, of 100 random individuals (sample preserved in 10% formalin). Record volume on catch log. - if a growth experiment is to be conducted, 100 individuals are selected randomly and put in a separate bucket and placed in the aquarium room - individual or groups of krill identified, measured and frozen for chemical composition and condition factor; vial numbers and numbers of animals in vials recorded - obtain the volume of krill that are not preserved, frozen or used in experiments measured - total volume and numbers of krill calculated (b) FISH All fish larvae are removed and immediately preserved in 95-100% ethanol in 20 ml scintillation or 7 ml glass vials. The larvae are counted and identified asap. All adult fish are removed and frozen in ziplock bags labeled inside and outside in -70 freezer. Pleuragramma antarcticum adults are frozen individually, after being measured for total and standard length and weighed on a spring scale. (c) SALPS The total volume of all salps is measured with a graduated cylinder with holes drilled in the bottom. A random subsample (~300-500 ml) of the total volume is sorted into size categories, and counted and volume determined for each size category: small (0-35 mm); medium (35-50 mm); large (50-70 mm); and extra large (>70 mm). Several individuals from each size category are preserved with the sample to verify species identification. (d) rare species are separated, idenitifed and counted for the entire sample: euphausiids to species pteropods: to genera (Limacina and Clione) amphipods: T. gaudichaudii and all others chaetognaths: large ones counted, small ones noted (e) presence noted heavy phytoplankton copepods (f) the volume of the remaining common organisms is measured in a graduated cylinder with holes drilled in the bottom, and all individuals from a subsample of that volume identified and counted; these species are usually Thysanoessa, Limacina, Themisto gauchichaudii, E. frigida, E. crystallorophias or a combination of several of the above. (g) all rare organisms, type specimens of salps, and either the subsample of common organisms or the entire sample are preserved together in 10% formalin (2) KRILL Total Length/Mature Female (for Euphausia superba only) Total length (TL) is standard length 1, or the length from the tip of the rostrum to the tip of the uropods excluding spines (Mauchline, 1981), measured with digital calipers. MF refers to the red thelycum on the female and indicates the females that have entered the reproductive cycle. A random sample of 100 individuals is measured/observed. The volume of these 100 individuals is measured with a graduated cyclinder with small holes drilled in the bottom to let water drain. If the 100 animals are of one size class, just these 100 krill are preserved for later analysis of physiological maturity stage. If the 100 animals are of two or more size classes, then an additional random sample of about 100 individuals (volume measured) is preserved along with the 100 measured individuals. The total volume preserved is recorded. Tows are done at standard stations along the cardinale lines, i.e., the onshore/offshore resolution is 20 km, and alongshore is 100 km. This is the same spatial resolution as for other biological and physical data. The standard depth for this tow was set to correspond to the deepest depth at which krill schools have been observed in this region. The primary objective for the 2-M trawl collections is to verify the alternate scatterers for bioacoustic data and to collect krill for experiments. Targeted tows are set for the depth of the acoustic trace. Observations and catch processing information, and disposition of catch are recorded on three forms for each event: trawl record, trawl catch log, and krill catch length frequency. The information on the trawl record and trawl catch log for each event is summarized in two files found in trawlgen/: trawl.list and trawl.catch. Detailed data on E. superba is found in two files for each event, ***.raw and ***.LFHIST. zooplankton community composition, length frequency of euphausia superba, reproductive stage ascii The first line is the number of columns (i.e. variables), followed by !, with study information after the !. Each following line identifies the variable and unit. Data follows in comma separated variable format. ~lter/~lterdata/94jan/* robin's mac /94jan/trawlgen trawl.list trawl.catch /94jan/trawl2m altscatter.dat krill.lfhist/evt#.lfhist krill.raw/EV#T#.raw.txt Robin M. Ross, Langdon B. Quetin none Robin M. Ross, Langdon B. Quetin Robin M. Ross, Tim Newberger, Jen Zamon, Kathi Neidermeyer, Chris Johnson, Sharon Stammerjohn On board sample analysis by above. Robin M. Ross, Kathi Neidermeyer, Chris Johnson Robin M. Ross, Langdon B. Quetin inspected the data sets for quality control. Robin M. Ross *.raw and *.lfhist submitted 15 May 1995 trawl.list and trawl.catch submitted 19 December 1996 Keys used to identify species: ¥ Kellerman, A. (ed.). 1989. Identification key and catalogue of larval Antarctic fishes. BIOMASS Scientific SEries No. 10. ¥ Gon, O., and P.C. Heemstra (eds.). 1990. Fishes of the Southern Ocean. J.L.B. Smith Institute of Ichthyology, Grahamstown, 462 pp. 12 pls. ¥ FAO Southern Ocean identification guides ¥ Makarov, R. Larval development of the antarctic euphausiids. BIOMASS Handbook No. 3. SCAR/SCOR/IABO/ACMRR, Group of specialists on living resources on the southern Oceans. ¥ Mauchline, J. Key for the identificaiton of antarctic euphausiids. BIOMASS Handbook No. 5. SCAR/SCOR/IABO/ACMRR, Group of specialists on living resources on the southern Oceans. Plots of length-frequency distributions are inspected for outliers, and unpredicted size animals in certain locations. Original records are checked to verify these outliers. Spread sheets for each tow are laid out to automatically calculate the split factor due to subsamples both pre-preservation and during sample analysis after preservation. Calculations are set up to arrive at the same number in two separate routes to check that all factors have been incorporated. Trawl.list and trawl.catch information has been proof read, and checked against original records.

Datafile Form V1.2 for describing a data file.